A Compliant PneuNets Linear Actuator with Large Off-Axis Stiffness

Soft pneumatic linear actuators are crucial elements in soft robots. Although those highly flexible and extensible actuators accelerate the development of soft robots, their inherent softness leads to significant disadvantages such as low load-carrying capacity and large motion error limit. In this paper, we propose a new class of soft pneumatic linear actuators with a compliant parallelogram mechanism as a backbone combined with Pneumatic network (PneuNets) bending actuators. The new actuator has flexibility in the motion direction while maintaining a higher stiffness in other directions. We derive the actuator’s pressure-displacement model by the Pseudo-rigid-body model and validate it by experiments and simulations. The stiffness measurement results show that the off-axis stiffness in the Y and Z directions are 188.327 and 5.469 times the in-axis stiffness, respectively. The proposed soft linear actuator design offers an alternative solution for enhancing the performance of soft robots.